Light circuit alarm system



R w. McBRlEN 2,397,028 LIGHT CIRCUIT ALARM SYSTEM' Filed May 21, 1942 .5 Shees-Sheet 1 Marchv 19, 1946.

March 19, 1946.v R, w. MCBRIEN 2,397,028

l LIGHT CIRCUIT ALARM SYSTEM Filed'May 21, 1942 s sheets-sheet 2,

March 19, 1946. v J R. w. MBRlEN 2,397,028

LIGHT CIRCUIT ALARM SYSTEM Filed may 21, 1942 :s sheets-sheet s e 2% z3 z5 3 Zi ,9 z/ L n ,73x fz l v /A//n/roz:

rrozA/EK Patented Mer. 19, 1946 rrics 2,397,028 LIGHT CIRCUIT ALARM SYSTEM Roger W. McBrien, Alton, Ill.

Application May 21,1942, Serial No. 443,881

2 Claims. l (Cl. 177-356) My invention has relation to improvements in electric alarm circuits and it consists in the novel features of construction more fully set forth in the specification and pointed outin the claims.

The present invention is an improvement over that shown in Patent No. 2,021,423 granted to Roger W. McBrien and Norval F. Wilson on November 19, 1935, and like said invention is particularly directed to electric circuits which may be connected to various power circuits in buildings and residences primarily for sounding and otherwise giving alarm in case of fire, burglary, or overload resulting from a short circuit.

The principal object of the present invention is to simplify the alarm circuit of the patent above referred to and to adapt said circuit for the use of standard electrical apparatus such as relays.

circuit breakers, etc., that are readily-procurable on the market. In other words, specialized apparatus is eliminated except for the thermostatic switch' assembly which sets the fire alarm in operation.

It is also one of the objects of the present invention to provide a thermostatic switch assembly that is a compact unitary device such that it may be readily connected into any circuit that is to be protected.

It is a further object of the invention to'emhouse service) circuit; Fig. 2 is also a diagrammatic representation of thealarm circuit showing the signal selector unit and associated relays and should be considered in connection with Fig. 1 with which it forms a part; Fig. 3 is a top plan of the fire alarm switching unit; Fig. 4 is a side elevation thereof; Fig.,5 is also a side elevation at.

an angle of 90 from that of Fig. 4; Fig. 6 is a vel'- tical cross-sectional detail taken on th'e line 6--6 of Fig. 5; and Fig. 7 is a cross-sectional detail taken on the line I-l of Fig. 3.

Referring to the diagrammatic view (Fig. 1) I and A2 represent the conductors of a power line to which are connected (in a manner` about to be described) service or power circuits C, C'. Obviously there is no limit to the number of circuits C that may be protected by my improved alarm system. l

A main circuit breakerV comprising a coil 3, switch element l, and contact 4 is connected to conductor kI and to coil 5 of a power supply relay- A. The end of coil 5 connected to contact 4' is also connected by a conductor a to contact 6 which is normally engaged by armature 1 of the relay which, in the -event of power failure, becomes disengaged from contact 6 and engages contact B'.

The armature 'i is connected to lconductor b` which vleads to one end of the primary coil of a transformer TandI also to junction points 8, 8 which are connected respectively to branch circuit4 breakers 9, 9' connected to circuits C, C' respectively,asfo1lows: v

Branch circuit breakers 9, 9' are identical in construction and may be described together. Each circuit breaker has a switch element I I normally in engagement with contact I2 connected to junction point 8, said switch element also being connected to one end o! coil I3, the other 4 end of said coil being connected by conductor d voi' circuits C, C' the ilow of power is from line wire I through main circuit breaker coll 3, switch of connection with the power line and power (or The circuits C, C' have the usual lamps and lreceptacles represented by devices I4 and I5 for the utilization of their power, but in addition thereto are also` provided with re alarm switching unit I6 and a burglary alarm switching unit The fire alarm switching unit (illustrated in Figs. 3 vto 7, inclusive)- comprises a pair of L- shaped metallic brackets I8, I8 secured in opposing relation on a. hollow threaded stem I9 terminating at its yupper end in a head 20 between which and a nut 2l said brackets are clamped.l The brackets Il, Il' are also connected to an asymmetric cell m which is clamped between them. The upright portions of the brackets are also connected to an insulating disc 22 on which are mounted spring contacts 23 and 24, the former being disposed above the disc 22 and the latter below. A fixed contact 25 is secured to the disc 22 in proximity to spring contact 23 and has electrical connection through a screw 26 withv a bracket 21 arranged beneath disc 22.

It will be observed that the spring contact 24 has an upwardly extending portion 24' in proxlmity to a contact 28 formed integrally with bracket I8, and a hook 24 is formed at the extremity of the portion 24', between which and bracket 21 a trip link 29 is connected. The function of thetrip link 29 is to hold the spring con-v tact 24 out of engagement with the contact 28. The upwardly extending portion of supporting bracket I8' is connected to contact 25 by a fusible link 30. VNormally the spring contact 23 is held out of engagement with iixed contact 25 by a nut 3| capable of operating as a fusible thermo element, which nut is screwed over the threaded extremity 32 of stem I9, and impinges on the end of a stem 33 which traverses the hollow stem I9, passing through but having no connection with spring contact 24 and iixed to the spring contact 23.

When the nut 3| is screwed in place it pushes upwardly on stem 33 and holds the spring contact 23 out of contact with the ilxed contact 25. The rounded end 3| of the; nut is held in place tor unit and the nre and burglary alarm relays are as follows:

A conductor 41 leads from one end of the secondary of transformer T to coil 48 of fire alarm relay and coil 49 of burglary alarm relay, the opposite ends of said coils being connected respectively by conductors 50 and 5I to contacts 52, 53 of delay thermo-switch unit 54. Contacts 52 and 53 are connected respectively by conductors 55 and 56 to heater resistors 51 and 58 operable on being heated to cause switching elements 59 and 60 to contact with' contacts 52 and 53. The switching elements 59 and 50 are also connected by means of conductors 8| and 52 to the signal selector unit 44 in a manner presently to appear.

Within the signal selector unit 44 there is a I resistor 63 and operating coll 84 for the tire alarm,

on the nut 3| by a solder. having a low melting point so that when the nut is exposed to temperatures above atmospheric temperature, the extremity 3|" will fall lfrom the nut, releasing the stem 33 and permitting spring contact 23 to engage xed contact 25. The spring contact 24, when released by the destruction of the fusible link 30, is urged upwardly by a coiled spring 33 disposed over stem 33 and' confined between head 20 of stem I9 and an insulating member 34 bearing against the underside oi spring contact 24.

The burglary alarm switching unit l1 comprises a switch 38 connected to conductor e and to a spring contact 31 held normally out of engagement with fixed contact 38 by a fusible link 39 which is also connected to conductor e' Connected in parallel with the parts just described is a fusible link 40, asymmetric cell 4I and contact 38. When the switch 36 is closed by unauthorized entry on the premises the current from the high voltage power circuit passes through fusible link 39 causing the effected branch circuit breaker to open a high voltage circuit and close a low Avoltage circuit, the current of which passes through link 39 melting the same and releasing spring contact 31 so that it will come into engagement with contact 38. The effect of this action on the circuit will be described in connection with the description of the operation of the burglary alarm circuit. f

I will now describe the apparatus employed to give the alarms when either of the service circuits C, C' is closed through the operation of either the re alarm or burglary alarm switching units l5 or |1.

A burglary alarm relay 42 and ilre alarm relay 48 are operatively associated with a signal selector unit 44 for the purpose of causing either the fire valarm or burglary alarm 46 to operate, depending upon whether the fire alarm switching unit Il or burglary alarm switching unit l1 has been actuated. The circuits including the signal selecand a resistor 65 and operatingcoil 83 for the burglary alarm, all of which are connected in parallel with a resistor 81 through junction point 68. Resistor 61 is also connected through junction point B9 to half wave asymmetric cells 10 and 1| which are arranged to pass opposing one-half alternating current waves. The positive half wave asymmetric cell 10 is also connected by a conductor 12 to resistor 83 and operating coil 54 of the fire alarm, while the negative (-l half wave asymmetric cell 1| is connected by a conductor 13 to resistor 55 and operating coil 85 of the burglary alarm.

Operating coil S4, when energized, actuates an armature 14 which controls switch element 15 disposed between contacts 16 and 11. Operating coil 66 actuates armature 18 which controls switch elements 19 and 30, the former operating between contacts 8| and 82, while the latter operates to and from contact 83. Contacts 82 and 88 are respectively connected to switching elements 59 and of the delay thermo-switch unit 54 by the conductors 8| and 62. Contact 8l is connected by a conductor 84 Ito actuating coil 85 of `a trouble relay 88, the other end ofsaid coil is connected by a conductor 81 to contact |30, armature |29, conductor |39 to burglar alarm relay 42, fire alarm relay 43, conductors l l2. 41, transformer T back to line Wire 2 as hereinafter described.

Push button 88 for doorbell 89 is also connected to conductor 81.

Switch element 80 is electrically connected directly to-contacts 15, while switch element 419 is electrically connected directly to contact 11. Switch element 15 is connected by a conductor 90 toa junction point 9|, whence a conductor 92 leads to conductor b and a conductor 93 leads to one end of coil 94 of a reset relay 95, the opposite end of said coil being connected by a conductor 96 to a push button 91 for operating the l reset relay in a manner that will hereinafter i 99 and |00, the rst two being adapted for engagement with the switching member |0| and the latter being adapted for engagement with the switching member |02, which are caused to be actuated by -a cam lever |03, in turn put into operation by an armature |04 through the energizing of coil 48. The burglary alarm relay likewise has fixed contacts |05, |08 and |01. the

irst two being adapted for engagement with switch member |03 and the last being adapted for engagement with switch member |09, which are caused to be actuated by cam lever through armature under the iniluence of'v coil 49.

The switch member |0| is connected tov the secondary of transformer T by a conductor `||2 joined with conductor 41, while switch member |09 is connected by a conductor ||3- to switch member |02. Switchmember |08`is connected by a conductor ||4 to-contact 98. Contacts |00 and |01 are joined by a, conductor ||5, which conductor has electrical connection with junction point 9|. Conductor 3, which connects switch memthe doorbell 89, said doorbell also being connected by conductor |2| to push button 68. Contact |06 is connected by a conductor |22 which i leads to a conductor |23 connected to burglary alarm 46 and burglary alarm lamp |25, said alarm and lamp also being connected to conductor |2|.

Contact is connected byconductor |26 to junction point 68 in the signal selector unit.

In addition to coil 85 the trouble relay 86 has an armature |21 for actuating cam lever |28,

c which latter is eiective upon switch member |29, releasing the latter whenthe 'lever is tripped to disengage contact and engage contact |3I. Switch member1|29 has a contact |32 for engagement with contact |33 connected to contact 3|, preferably by a metallic reed |34. The member |34 is connected by a conductor |35 to auxiliary trouble indicating lamp |36 which is also connected to conductor |2|. The main trouble indicating lamp |31 is connected between conductor and conductor |2|.

The iire alarm 45 and the re alarm lamp |38 are connected in parallel between conductor ||9 and conductor |2|. Switch member |29 of trouble relay 86 is connected by conductor |39 to iixed contact |05 of the burglary alarm relay 42. A second burglary alarm lamp |40 is conrliected between conductor |23 and conductor A battery |4| is provided for use in the event of failure of the power line supplying the house circuits One'end of this battery is connected to contact 6' of power supply relay A, while the other end ofthe battery is connected in parallel to an alarm |42 and auxiliary lamps |43, |44, the opposite sides of said alarm and lamps being connected to conductorcl2i. The signal transmitter relay |45 includes a coil |46, armature |41 and trip lever |48, effective 'on switch element |49 whereby the latter is placed in electrical connection either with contact or |5|.

Normally the lever |48 is in position to hold,v

the switch element |49 in contact -with the'contact |50 but when the lever |48 is released by the actuationof armature |41 the switch element |49 moves outof contact with |50 and engages contact |5|. The engagement of the switch element |49 with contact |5| connects the plug receptacle |52 across the line wires and 2 so that any automatic signal transmitter (not shown) that may be connected to the receptacle |52 will be put into action. It is understood that the autransmitter relay are notnecessarily a part of the invention and may be dispensed 'with if desired.

The reset relay 95 is provided with an armature |53 which carries a frame |54 to the extremities of which are secured bars |55 and |56.

Bar |55 will engage the lever|28 while the latterl is in its lowermost position and the bar |56 will engage levers |03 and ||0 when in their lowermost positions, so that when the coil 94 is energized and the armature |53 pulled upwardly the I to force the same into electrical connection with of the power' line and 2 the grounded side which l services the premises to be protected. The cirframe |54 will also be raised so that the bars |55 and |56 will raise the levers |28, |03 and ||0, and restore themto their at-rest positions. There is an extension arm |51 projecting from the frame |54 which will engage the spring element |34 contact |32 when the reset relay coil 94 is energized. f

Having described the various parts and circuits that make up my improved light circuit alarm system, I of the device.

Referring to Figs. l and 2, is the high side shall now describe the operation cuit is from line wire through main circuit. breaker coil 3, switch element 4, contact 4', to holding4 coil 5 of power relay A. The magnetic attraction oi coil 5 holds the armature I-'in contact with contact 6 extending the p ower line to junction points 3, 8' of branch circuit-breakers 9, 9', respectively. .The power line is also extended to automatic signal transmitter |52 and the primary of transformer T, the other side of the transformer primary being connected to line wire 2. Since the branch circuit-breakers 9, 9' for the circuits C, C' are identical, only one will be described. f

Referring to branch circuit-breaker 9, the circuit continues from junction point 8 to contact I2 through the switch element |,to trip coil |3, conl Operation of fire alarm A better understandingy of the operation of the nre alarm will be had by referring to Figs. 3 to '1, inclusive, wherein the nre alarm switch unit is shown in detail. The heat of a re melts the fusible material 3|" causing the extremity 3| to fall from the nut 3| and release the stem 33 which allows spring contact 23 to engage with the iixed contact 2.5. The resulting current which flows through spring contact 23' also ows through fusible link 29 and contact 24, causing a momentary overload across the conductors e, e' of'circuit C.

Branch circuit-breaker 9 is tripped, opening the circuit through contact |2, which disconnects glar alarm relay 42, thence to junction point 68 of alarm selector 44 through switch members either |02 or |09 to conductors ||3, ||6, fuse ||1, conductor 8 and resistor 61. From the junction point 68 the current divides and ows through iive parallel parts to junction point 69 as follows:

ton'iatic signal transmitter and ofcourse signal 1st: From junction point 49 both positive and negative impulses ilow through resistor "to junction point 59. l

2nd: Positive impulses flow from junction point Il through resistor 93, positive (-l) 2*/2 wave rectiner unit 1o to junction point 99.

3rd: Positive (-l-l impulses flow from junction point 99 through coil 94, 1/2 wave rectiiler unit 10 to junction point 69. t.

4th: Negative impulses flow from junction point 4I through resistor 55, 1/2 wave-rectifier unit 1| to junction point S9. 1 f u 5th: Negative impulses flow from junction point 99 through coil 66, 1/2- wave rectifier unit 1| to junction point 99. From junction point 49 rthe alternating current flows through the bi-metalllc link |2, contact switch element coil |3, and fusible link 29 of the switching unit l5. The heat oi the current which thus flows through link 29causes said link to fuse so that the current will now iiow through the fusible link 30 and the positive 1/2 wave rectifier unit (asymmetric cell m') to bracket 25', spring contact 24, spring contact 23, back to the line wire 2.

While the link 29 was fusing and before the circuit therethrough was broken the following op- 'eration took place: Coils 64 and 96 of the signal selector unit 44, having been energized, actuated their respective armatures 14 and 19, the former moving the switch element -15 out "oi contact from the contact I9 and into engagement wtih the contact 11 while the latter armature 18 causes switch velement 1.9 to move away from 'contact 92 and into engagement with contact Il. At the same time switch element l0 is moved into 'engagement with contact 93. As aresult of this operation, acurrent flows from the power supply line through junction point 9|, contact points 11 and 9|, and coil l5 of trouble relay 96. Current willalso flow through contactl |99 and |95 of the burglaralarm relay 42 and contact 99 of fire alarm relay 43,

thence through the line wire'41 and the secondary coil of the transformer T back to line 2.

The current from the high voltage line breaks the connection between switching armature |29 and contact |39 in the trouble relay 89 and closes the circuit through contact |3|. This causes the trouble indicating lamp |31 to be energized, as well as auxiliary trouble lamp |36.

'Ihe doorbell 99, togetherwith its switch button 49, were' rendered inoperative when the switching element |29 broke contact with the contact |39. The normal operating circuit for the bell 49 ls lfrom the low voltage line 41 through contact 94, |95, |30, push-button I9, bell 99, conductor |2|, conductor f, and line wire 2.

Selective function. of rectifier vunitslor jre alarm After the fusing of link 29 which resulted in the closing of the circuit from contact 24, 24' to contact 28, as above stated,'.the current which flowed through the plus (-4-) l/ wave rectier unit m acted in a selective manner as follows:

'I'he plus (-l-l 1/2 wave current flowed fromcon ductor 41 to contact 98 of the re alarm relay 43, contact |95 of the burglar alarm relay 42, junction point 68, alarm selector coil 64, plus (-l-l 1/2 wave rectifier unit 10. junction point 69, bi-metallic strip I2'. contact coil I3, conductor d, conductor e, spring contact 24, contact 29. to bracket I9 asymmetric cell m `to bracket I8', clearing fuse 30, contact 25 to spring contact 23 to conductors e' and f back to line wire 2 and the secondary of transformer T. The plus (-l-l 1/2 of the current wave cannot flow through coil 96 or resistor S5 to junction point 49 as it is blocked by the minus 1/2 wave rectifier unit 1|, and the minus 1A of the wave cannot pass through the plus V2 wave rectifier unit m.

The fire alarm circuit The re alarm circuit is completed as follows: From contact 6 to conductor h, to conductor 92, to junction point 9|', contact 11 (now engaged by switching armature 15), contact 92, conductor 6|, to bimetal 59 loi.' the time relay 54, to resistor 51 of the time relay 54 to coll 49 of ilre alarm relay 43, then to line wire 41, to transformer T, and power line 2. The current ilow through resistor 51 causes the resistor to impinge upon contact 52 in a period oi' approximately from four to five seconds, after which suiilcient current flows through coil 48 to energize the same and attract its armature |04 which trips latch |93 and allows the switching elements 9| and |92 to engage contacts 99 and |00. The closing of the gap between contact 99 and switching element |9| completes the circuit of the local alarm bell (or siren) 45, as wel! as that of the lamps |39, |29, and coil |46 of the signal transmitter relay |45.

The energizing of coil |49 results in the operation of the manual reset transmitter relay |45. together with the breaking of the contact between switching element |49 and contact |50 and the making of contact between said switching element and the contact i5 I, which completes the connection of the signal transmitter receptacle |52 as it is now connected directly across the power lines and 2 through contact 5 and contact |5I.

The closing kof the gap between contact and switching member |92 completes the circuit from line wire through armature 1, conductor b. conductor 92, junction point 9|, conductor H9, conductor IIS, lag-fuse conductor H9, conductor h, conductor g, bi-metallic strip l2', flexible lead y, contact switch element coil |3, conductor d, conductorie, spring contact 24, contact 2'8, to bracket |8 asymmetric cell m to bracket |8', clearing fuse 30, contact 25 to spring contact 23 to conductors e' and f back to line wire 2. The resistance of this circuit is such as to limit the flow of current to safe limits and the clearing fuse 39 operates more quickly and at lower current value' than the lag-fuse or bi-metallic strip I2. The destruction of clearing fuse 3l restores the lighting service to the circuit C through the branch circuit-breaker 9. The bimetallic strip I2' and the lag-fuse act as a The fire alarm relay may be reset by means of the push-button 91 and the reset relay 95. Upon closing push-button switch 91, the current flows'from conductor 93 through coil 94 and the switch 91', through conductor |2| to line wire 2.

The operation of the relay 95 restores the flrc alarm relay 43, burglar' alarm relay 42, and the trouble relay 86, through the lifting of the plunger armature |53 and the associated frame |54, together with its bars |55 and |56, in a manner well understood in the art. K

While the reset relay 95 is energized, extension arm |51 projecting from the frame |54 operates to holdvspring element |34 in contact with the contact |32r so as to close the circuit through the trouble lindicating lamp |31. If for some reason the armature |53, together with its frame |54,

`asoman should fail to release when the push-button 91 is released. the continuous 'glowing or the lamps |31 e and |38 will indicate that there is trouble so that ,the proper steps may be taken to rectify the same.

Under these conditions the circuit through lamps Burglar alarm The operation of the burglar alarm unit l1 is l similar to that of the fire alarm unit s in that with the closing of the burglar alarm switch 38, a circuitis completed across the conductors e and e' through fusible link 38. The resultant flow of current immediately actuates the switching armature I|, disconnecting the power line from the branch circuit-breaker 9 and closing a circuit from the secondary of transformer T, through the nre and burglar alarm relays (similar as in the case ofthe closing of the iire alarm unit i8), to

the fusible link 33, and finally line wire 2.

The destruction of the link 39 allows the switching member 31 to-contact with the contact' 38, whereupon the low voltage negative 1/2 wave rectified impulses from the transformer T' flow through the ,fire alarm and burglar alarm relays and selector relays to the switch 36, negative V2 wave rectifier unit 4|, fuse 40, and lin'e wire 2.

The burglar alarm side of the selector unit 44 now operates to open the circuit between switching armature 19 and contact 80 and close the same from said switching armature to contact 8 This action completes the circuit from line wire to conductor 92, junction point-9|," switching armature 15, contact 18, switching armature 80,v

contact 83, conductor 82, -to the resistor 58 of the burglar alarm time relay 54, thence through conductors 58 and 5| to coil 49 of the burglar alarm relay 88 and to the secondary-of transforme;` T. The iiow of current through the-thermo-resistor junction points 88 and 89, conductors h and a, to the bi-metallic strip I2', contact switching element coil |73, conductor d, and thence through the short circuit to the line wire 2. 'The warping of the bi-metallic strip |2' opens the circuit between switching element and contact l', disconnecting the low voltage power from the circuit. The circuit can only be restored toloperative condition by removing the short and resetting the branch circuit-breaker 9 or 9', as the case may be. The action ofthe bi-metallic strip I2' is not instantaneous so that a suitable time delay is provided to complete the operation, as in the case of a re or burglar alarm. The coils 84 and 88 of the signal selector unit 44 are effected by both plus and minus impulses of the alternating current wave so that coil 8 8 operates armature 18 to break the connections between switching elements 19, 80 and contact 9|, 82. Coil 84 actuates.

armature 14 so as to break the connection between switching element and contact 18 and make connection between said switching element and contact 11. There is now a current ow from the high voltage power supply line, conductor b, cony ductor 92, junction point 9|, conductor 90, conductors 11 and 8|, conductor 84, to coil 85 of the trouble relay 88, thencer to contact |30, switching element |29, conductor |39, to contact |05 of the burglar alarm relay 42, contact 98 of the fire alarm relay 43, thence through conductors ||2 and 4|, to the secondary of the transformer T,

back to line wire 2.

80 closes the gap therebetween and the contact 53, permitting suicient current to flow through the coil 83 to trip the latch ||0 and operate the burglaralarm relay 42. In the operation of said relay, the switching armature |08 breaks contact with the contact |05 and makes contact with contact |08 while the switching armature |09 makes contact with contactl |01, thus energizing the alarm 48 together with lamps |25 and |40. The

circuit is from the secondary of transformer T* through switching armature |0|, to contact 98, conductor ||4, to switching armature |08, to contact |08, to` conductor |22, conductor |23, alarm 48, in parallel with the lamps |25 and |40, all of which are connected to conductor |2| leading back to line wire 2.

The burglar alarm relay is reset in the same 'manner as the fire alarm relay.

Eect of short circuit Operation of trouble relay lamps 137 and136 -The high voltage current from the line actuates the trouble relay 88 and causes the openingv of the connection between switching element |30 .and contact |29 and the closing of the connec- 1 tion between said switching element and contact |3|. eating lamps |31 and |38 as follows: From the conductor 41, switching element |0|, contact 38, conductor ||4, switching element |08, contact |05, conductor |39, switching element |29, contact |3|, conductor |35, lamps |31 and |38, conductor |2|, to line wire 2. The auxiliary trouble lamp |38, being in parallel with lamp |31, is also energized.

Doorbell rendered inoperative Since the doorbell circuit includes switching element |29 and contact |30, the breaking of this contact through the operation of the trouble relay renders the doorbell inoperative, and giving supervisory feature to the circuit.

. Power -fayilure In the event of a power failure the coil 5 of relay `A will `release its armature 1, breaking the circuit From `the foregoing it should be apparent that in the event lof a lire in either service circuit C or C', the re alarm relay 43 is actuated through the coils 83 and 84 of the signal selector unit 44;

This operation energizes the trouble indion the other hand, when either of the burglar alarm switches 3B are closed, the burglar alarm relay l2 is activated through coils l! and of the signal selector unit. j Thus the signal selector unit responds either to the thermally operated switch 23 to close the fire alarm circuit and cause nre alarm I5 to sound or to the mechanical switch 36 to close the burglar Aalarm circuit and cause the burglar alarm 4l to sound.

While I show electrical means for resetting the fire and burglar alarm relays, mechanical means could also be used.

Having described my invention, I claim:

1. A power and alarm system comprising a power circuit connected to an alternating current source of electric power, a lire alarm switching unit and a burglar alarm switching unit connected across the power circuit, a thermo-electric yswitch connected in and controlling the action of theflre alarm switching unit, a mechanical switch connected in and controlling the action of the burglar alarm switching unit, a transformer having its primary connected across the power circuit, a circuit breaker connected in series with the power circuit and transformer primary, fire and burglar alarm relays, said circuit breaker having a switch element and contact for connecting both the fire alarm and burglar alarm switching units tothe transformer secondary, a signal selector unit having a pair of switch-actuating coils and switch contacts connected in parallel between the circuit breaker and theflre and burglar alarm relays, fire and burglar alarm circuits, asymmetric cells connected in series respectively with the thermo-electric switch of the nre alarm unit and the mechanical switch o( the burglar alarm unit, and an asymmetric cell connected in series with each of said switch actuating coils.

whereby said switches are selectively actuated to connect either the nre or burglar alarm relays to the transformer secondary and thereby close either the lire or burglar alarm circuit.

2. A power and alarm system comprising a power circuit connected to an alternating current source of electric power, aflre alarm switchins unit and a burglar alarm switching unit; connected across the power circuit, a thermo-electric switch connected in and controlling the action of the fire alarm switching unit, a mechanical switch connected in and controlling the action of the burglar alarm switching unit, a transformer having its primary connected across the power circuit, a circuit breaker connected in series with' the power circuit and transformer primary, nre and burglar alarm relays, said circuit breaker having a switch element and contact for connecting both the firev alarm and burglar alarm switching units to the transformer secondary, a signal selector unit having a pair of switch-actuating coils and switch contacts connected in parallel betweenthe circuit breaker and the lire and burglar alarm relays, hre and burglar alarm circuits and trip links associated with the thermoelectric switch and burglary alarm switch, auxiliary switches actuated by said trip links, whereby the power circuit is lopened and the alarm circuit closed, asymmetric cells connected in series 4respectively with the thermo-electric switch of the fire alarm unit and mechanical switch of burglar alarm unit, and an asymmetric cell connected in series witheach of said switch actuating coils, whereby said switches are selectively actuated to connect either the nre or burglar alarm relays 'to the transformer secondary and thereby close either the fire or burglar alarm circuit.

' ROGER W. McBl'tIEN.v 

